1. [Field of the Invention]
The present invention relates to a method for producing a composited particle, a composited particle produced by this method and an aqueous dispersion for chemical mechanical polishing containing the composited particles, and a method for producing an aqueous dispersion for chemical mechanical polishing.
2. [Description of the Prior Art]
As a polishing material used for chemical mechanical polishing such as element surfaces and interlayer insulation films in semiconductor devices and the like (which hereinafter may sometimes be referred to as xe2x80x9cCMPxe2x80x9d), an aqueous dispersion containing inorganic particles such as colloidal silica, colloidal alumina and the like is conventionally often used. However, this aqueous dispersion containing inorganic particles has low dispersion stability and tends to coagulate, and consequently, a defect occurs on a surface of polishing wafer (hereinafter, referred to as xe2x80x9cscratchxe2x80x9d) by the coagulates, causing lowering of the yield. For solving this problem, there have been suggested various methods such as (1) a method in which a surfactant is compounded into an aqueous dispersion, (2) a method of uniform dispersion by a homogenizer and the like, (3) a method in which the coagulates are removed by a filter, and other methods. However, these methods do not improve a polishing material itself, and additionally, may also cause new problems such as reduction in polishing rate, staining of a surface of polishing wafer by a metal ion, and the like.
Recently, lowering of the dielectric constant of an interlayer insulation film aiming at improvement of the performance of VLSI is noticed. For this lowering of dielectric constant, there have been developed, in substitution for an SiO2 film having a high dielectric constant, interlayer insulation films made of fluorine-added SiO2 (dielectric constant: about 3.3 to 3.5), polyimide-based resins (dielectric constant: about 2.4 to 3.6, manufactured by Hitachi Chemical Co., Ltd., trade name: xe2x80x9cPIQxe2x80x9d, manufactured by Allied Signal Corp., trade name: xe2x80x9cFLARExe2x80x9d, and the like), benzocyclobutene (dielectric constant: about 2.7, manufactured by Dow Chemical Corp., trade name: xe2x80x9cBCBxe2x80x9d, and the like), hydrogen-containing SOG (dielectric constant: about 2.5 to 3.5), organic SOG (dielectric constant: about 2.9, manufactured by Hitachi Chemical Co., Ltd., trade name: xe2x80x9cHSGR7xe2x80x9d, and the like), and the like. However, these insulation films have lower mechanical strength, are soft and fragile as compared with an SiO2 film, and therefore, when conventional aqueous dispersions containing an inorganic particle is used for CMP, disconnection of wiring may sometimes occur due to the generation of scratch and the like, inviting further lowering of the yield.
Further, Japanese Laid-open Patent Publication No. 86216 of 1995 discloses a method for polishing a working film of a semiconductor device with a polishing material containing not an inorganic particle but an abrasive particle mainly composed of organic polymer and the like. By this method, an abrasive particle remaining on a surface of polishing wafer after polishing can be burnt and removed, and occurrence of defects on products such as a semiconductor device and the like due to the remaining particle can be suppressed. However, it has a problem in that since a particle made of organic polymer has lower hardness as compared with an inorganic particle such as of silica, alumina and the like, polishing rate can not be increased sufficiently.
Furthermore, Japanese Patent Publication No. 40951 of 1994 discloses a method for producing a composite particle by mixing particles in which having the zeta potentials of opposite signs. However, in this method, since each particle adheres only by an electrostatic force, there is a possibility of separation of the particle when a large shearing stress is applied on the composite particle, and the like. Also, in this method, since the particles to be mixed have the zeta potentials of opposite signs, mixing speed should be controlled, a large coagulate may be formed depending on this speed, and this coagulate may give scratch in polishing, causing lowering of the yield of products.
[Problems to be Solved by the Invention]
An object of the present invention is to provide a method for producing composited particles in which inorganic particles which have been made composite are not released, composited particles produced by this method, and an aqueous dispersion for CMP containing these composited particles.
A further object of the present invention is to provide a method for producing an aqueous dispersion for CMP in which generation of coagulates in production is prevented.
[Features of the Invention]
According to the present invention, a method for producing composited particles, composited particles and an aqueous dispersion for CMP, and a method for producing an aqueous dispersion for CMP, having constitutions described below are provided to solve the above-mentioned objects.
[1] A method for producing a composited particle comprising forming a preliminary particle by adhering one or more types of inorganic particles on at least a part of the surface area of a polymer particle, then, polycondensing at least one selected from among organosilicon compounds and organometal compounds in the presence of said preliminary particle.
[2] The method for producing a composited particle according to [1] above, wherein said inorganic particle is adhered to said polymer particle via a connecting compound.
[3] The method for producing a composited particle according to [2] above, wherein said connecting compound is a silane coupling agent.
[4] The method for producing a composited particle according to [1] above, wherein said inorganic particle is of at least one selected from among alumina, titania and ceria.
[5] The method for producing a composited particle according to [4] above, wherein said polymer particle has at least one selected from among carboxyl groups, anions thereof, sulfonate groups and anions thereof.
[6] The method for producing a composited particle according to [4] above, wherein at least one selected from among negative surfactants and negative water-soluble polymers is adsorbed or chemically-bonded to said polymer particle.
[7] The method for producing a composited particle according to [1] above, wherein said inorganic particle is of at least one selected from among silica and zirconia.
[8] The method for producing a composited particle according to [7] above, wherein said polymer particle has at least one selected from among amino groups and cations thereof.
[9] The method for producing a composited particle according to [7] above, wherein at least one selected from among positive surfactants and positive water-soluble polymers is adsorbed or chemically-bonded to said polymer particle.
[10] The method for producing a composited particle according to [1] above, wherein said inorganic particle is adhered to said polymer particle by an electrostatic force.
[11] The method for producing a composited particle according to [10] above, wherein said inorganic particle is of at least one selected from among alumina, titania and ceria.
[12] The method for producing a composited particle according to [11] above, wherein said polymer particle has at least one selected from among carboxyl groups, anions thereof, sulfonate groups and anions thereof.
[13] The method for producing a composited particle according to [11] above, wherein at least one selected from among negative surfactants and negative water-soluble polymers is adsorbed or chemically-bonded to said polymer particle.
[14] The method for producing a composited particle according to [10] above, wherein said inorganic particle is of at least one selected from among silica and zirconia.
[15] The method for producing a composited particle according to [14] above, wherein said polymer particle has at least one selected from among amino groups and cations thereof.
[16] The method for producing a composited particle according to [8] above, wherein at least one selected from among positive surfactants and positive water-soluble polymers is adsorbed or chemically-bonded to said polymer particle.
[17] The method for producing a composited particle according to [1] above, wherein said composited particle is formed by adhering a plurality of said inorganic particles on the surface area of said polymer particle.
[18] The method for producing a composited particle according to [1] above, wherein said composited particle is formed by coating at least 5% of surface area of said polymer particle by said inorganic particle.
[19] The method for producing a composited particle according to [1] above, wherein the average particle size of said composited particle is from 0.05 to 0.5 xcexcm, and at least 80% of said composited particle has particle sizes within a range of said average particle sizexc2x130%.
[20] A composited particle produced by a method according to any one of [1] to [19] above.
[21] An aqueous dispersion for chemical mechanical polishing, comprising composited particles produced by a method according to any one of [1] to [19] above.
[22] A method for producing an aqueous dispersion for chemical mechanical polishing, wherein the pH of an aqueous dispersion containing polymer particles and inorganic particles having the zeta potential of the same sign as that of said polymer particles is so changed that the zeta potential of said polymer particles and the zeta potential of said inorganic particles are of opposite signs, to form composite particles composed of said polymer particles and said inorganic particles.
[23] The method for producing an aqueous dispersion for chemical mechanical polishing according to [22] above, wherein said inorganic particles are of at least one selected from among alumina, titania and ceria.
[24] The method for producing an aqueous dispersion for chemical mechanical polishing according to [23] above, wherein said polymer particles have at least one selected from among carboxyl groups, anions thereof, sulfonate groups and anions thereof.
[25] The method for producing an aqueous dispersion for chemical mechanical polishing according to [23] above, wherein at least one selected from among negative surfactants and negative water-soluble polymers is adsorbed or chemically-bonded to said polymer particles.
[26] The method for producing an aqueous dispersion for chemical mechanical polishing according to [22] above, wherein said inorganic particles are of at least one selected from among silica and zirconia.
[27] The method for producing an aqueous dispersion for chemical mechanical polishing according to [26] above, wherein said polymer particles have at least one selected from among amino groups and cations thereof.
[28] The method for producing an aqueous dispersion for chemical mechanical polishing according to [26] above, wherein at least one selected from among positive surfactants and positive water-soluble polymers is adsorbed or chemically-bonded to said polymer particles.
[29] The method for producing an aqueous dispersion for chemical mechanical polishing according to any one of [22] to [28] above, wherein said composite particles are formed by coating at least 5% of the surface area of said polymer particles by said inorganic particles.
[30] The method for producing an aqueous dispersion for chemical mechanical polishing according to any one of [22] to [29] above, wherein the average particle size of said composite particles is from 0.05 to 0.5 xcexcm, and at least 80% of said composite particles have particle sizes within a range of said average particle sizexc2x130%.
[Effect of the Invention]
According to a method for producing a composited particle described in herein, composited particle can be obtained which is composed of a polymer particle and an inorganic particle, the surface of which has sufficient strength and hardness, which is excellent in heat resistance and is appropriately soft, and in which an inorganic particle which has been made composite is not released. A composited particle of described herein produced by the above-mentioned method is useful in CMP such as working films of a semiconductor device and the like since this particle has the above-mentioned properties. Further, according to an aqueous dispersion for CMP described herein containing a composited particle produced by the above-mentioned method, the polishing rate of a working film can be increased, and also when applied to a surface of polishing wafer carrying an interlayer insulation film having lower strength, the occurrence of scratch, disconnection of wiring, and the like can be suppressed.
According to a method for producing an aqueous dispersion for CMP described herein, the yield of a product is high since generation of coagulates in production is prevented. Further, the resulted aqueous dispersion for CMP contains composite particles composed of polymer particles and inorganic particles, can increase the polishing rate of working films, and at the same time, can suppress generation of scratch, disconnection of wiring and the like also when applied to a surface of polishing wafer carrying an interlayer insulation film having lower strength.